Semiconductor device including oxide semiconductor

Abstract

A semiconductor device which occupies a small area is provided. A semiconductor device includes a resistor. The resistor includes a transistor. The increase rate of a drain current of the transistor with a 0.1 V change in drain voltage is preferably higher than or equal to 1% when the drain voltage is higher than a difference between a gate voltage and a threshold voltage of the transistor. The semiconductor device has a function of generating a voltage based on the resistance of the resistor.

What is claimed is: 
     
       1. A semiconductor device comprising:
 a first transistor, a second transistor, a third transistor, a fourth transistor, and a fifth transistor each including a gate, a source, and a drain; and 
 a first wiring, a second wiring, and a third wiring, 
 wherein the gate of the first transistor is electrically connected to the first wiring, one of the source and the drain of the first transistor is electrically connected to the second wiring, and the other of the source and the drain of the first transistor is electrically connected to a first node, 
 wherein the gate of the second transistor is electrically connected to the first node, one of the source and the drain of the second transistor is electrically connected to the second wiring, and the other of the source and the drain of the second transistor is electrically connected to a second node, 
 wherein the gate of the third transistor is electrically connected to the second node, one of the source and the drain of the third transistor is electrically connected to the first node, and the other of the source and the drain of the third transistor is electrically connected to a third node, 
 wherein the gate of the fourth transistor is electrically connected to the third node, one of the source and the drain of the fourth transistor is electrically connected to the second node, and the other of the source and the drain of the fourth transistor is electrically connected to the third wiring, 
 wherein the gate of the fifth transistor is electrically connected to the third node, one of the source and the drain of the fifth transistor is electrically connected to the third node, and the other of the source and the drain of the fifth transistor is electrically connected to the third wiring, 
 wherein the first node is electrically connected to an output terminal, 
 wherein the first transistor further comprises:
 an oxide semiconductor layer electrically connected to the source and the drain of the first transistor; and 
 a gate insulating layer over the oxide semiconductor layer, the source, and the drain of the first transistor, 
 
 wherein the gate of the first transistor is positioned over the gate insulating layer and overlaps with the oxide semiconductor layer, and 
 wherein a bottom surface of the gate of the first transistor is positioned below a bottom surface of the oxide semiconductor layer. 
 
     
     
       2. The semiconductor device according to  claim 1 , wherein an increase rate of a drain current of the first transistor with a 0.1 V change in drain voltage is higher than or equal to 1% when the drain voltage is higher than a difference between a gate voltage and a threshold voltage of the first transistor. 
     
     
       3. The semiconductor device according to  claim 2 , wherein a cutoff frequency of the first transistor at a source-drain voltage higher than or equal to 1 V and lower than or equal to 2 V is higher than 2 GHz. 
     
     
       4. The semiconductor device according to  claim 1 , wherein the first transistor is capable of acting as a resistor. 
     
     
       5. The semiconductor device according to  claim 1 , wherein a channel length of the first transistor is less than or equal to 100 nm. 
     
     
       6. The semiconductor device according to  claim 1 , wherein the oxide semiconductor layer includes at least one of indium and zinc. 
     
     
       7. The semiconductor device according to  claim 1 , wherein the oxide semiconductor layer includes at least one of aluminum, gallium, yttrium, and tin. 
     
     
       8. The semiconductor device according to  claim 1 , wherein the gate of the first transistor overlaps with an upper surface of the oxide semiconductor layer and faces a side surface of the oxide semiconductor layer in a channel width direction with the gate insulating layer provided between the oxide semiconductor layer and the gate. 
     
     
       9. The semiconductor device according to  claim 1 , wherein the oxide semiconductor layer comprises a plurality of crystal parts with c-axis alignment. 
     
     
       10. A semiconductor device comprising:
 a first transistor, a second transistor, a third transistor, a fourth transistor, and a fifth transistor each including a gate, a source, and a drain; and 
 a first wiring, a second wiring, and a third wiring, 
 wherein the gate of the first transistor is electrically connected to the first wiring, one of the source and the drain of the first transistor is electrically connected to the second wiring, and the other of the source and the drain of the first transistor is electrically connected to a first node, 
 wherein the gate of the second transistor is electrically connected to the first node, one of the source and the drain of the second transistor is electrically connected to the second wiring, and the other of the source and the drain of the second transistor is electrically connected to a second node, 
 wherein the gate of the third transistor is electrically connected to the second node, one of the source and the drain of the third transistor is electrically connected to the first node, and the other of the source and the drain of the third transistor is electrically connected to a third node, 
 wherein the gate of the fourth transistor is electrically connected to the third node, one of the source and the drain of the fourth transistor is electrically connected to the second node, and the other of the source and the drain of the fourth transistor is electrically connected to the third wiring, 
 wherein the gate of the fifth transistor is electrically connected to the third node, one of the source and the drain of the fifth transistor is electrically connected to the third node, and the other of the source and the drain of the fifth transistor is electrically connected to the third wiring, 
 wherein the first transistor further comprises:
 a first oxide semiconductor layer; 
 a second oxide semiconductor layer over the first oxide semiconductor layer, the second oxide semiconductor layer electrically connected to the source and the drain of the first transistor; 
 a third oxide semiconductor layer over the second oxide semiconductor layer, the source, and the drain of the first transistor; and 
 a gate insulating layer over the third oxide semiconductor layer, the source, and the drain of the first transistor, 
 wherein the gate of the first transistor is positioned over the gate insulating layer and overlaps with the second oxide semiconductor layer, and 
 wherein a bottom surface of the gate of the first transistor is positioned below a bottom surface of the first oxide semiconductor layer. 
 
 
     
     
       11. The semiconductor device according to  claim 10 , wherein an increase rate of a drain current of the first transistor with a 0.1 V change in drain voltage is higher than or equal to 1% when the drain voltage is higher than a difference between a gate voltage and a threshold voltage of the first transistor. 
     
     
       12. The semiconductor device according to  claim 11 , wherein a cutoff frequency of the first transistor at a source-drain voltage higher than or equal to 1 V and lower than or equal to 2 V is higher than 2 GHz. 
     
     
       13. The semiconductor device according to  claim 10 , wherein the first transistor is capable of acting as a resistor. 
     
     
       14. The semiconductor device according to  claim 10 , wherein the first oxide semiconductor layer, the second oxide semiconductor layer, and the third oxide semiconductor layer each include at least one of indium and zinc. 
     
     
       15. The semiconductor device according to  claim 10 , wherein the first oxide semiconductor layer, the second oxide semiconductor layer, and the third oxide semiconductor layer each include at least one of aluminum, gallium, yttrium, and tin. 
     
     
       16. The semiconductor device according to  claim 10 , wherein the gate of the first transistor overlaps with an upper surface of the third oxide semiconductor layer and faces a side surface of the second oxide semiconductor layer in a channel width direction with the gate insulating layer provided between the second oxide semiconductor layer and the gate. 
     
     
       17. The semiconductor device according to  claim 10 , wherein the first oxide semiconductor layer, the second oxide semiconductor layer, and the third oxide semiconductor layer each comprise a plurality of crystal parts with c-axis alignment. 
     
     
       18. The semiconductor device according to  claim 10 , wherein the first node is electrically connected to an output terminal. 
     
     
       19. The semiconductor device according to  claim 10 , wherein the third oxide semiconductor layer is in contact with a side surface of the second oxide semiconductor layer in a channel length direction.